Okay, if you can keep the weight to 15-1/2 lbs and if the Moki can turn a 20-8 at 8500 rpm you'll have a great setup. You may even benefit with a 22x8 and lower rpm, as long as it stays over 7000, but I don't know how the Moki will react to the larger load. I would say with this setup you'll be able to do anything in the book.

Since you already have the Moki, why don't you try and get your own rpm data, say with a 20x8 and 22x8 Menz or MSC or Mejzlik prop? Real numbers with your engine and prop combo will eliminate some of the unknown.